COOPERATIVE COGNITIVE RADIO SPECTRUM SENSING USING A HYBRID DATA-DECISION METHOD

摘要

A spectrum sensing method for cognitive radio to detect spectrum holes in an environment of bandwidth scarcity. The method comprises first receiving a wireless signal at a cognitive radio user, and then discovering the frequency edges of allocated frequency bands by using wavelet transform coefficients to detect discontinuities in the power spectral density of the received signal. After determining the allocated frequency bands, the method determines frequency band availability by detecting the in band energy using a bi-threshold energy detector, where the energy detector makes hard decisions and soft decisions. Finally, a fusion center combines hard and soft decisions collected from a cooperative spectrum sensing network of cognitive radio users and makes a final decision using a hybrid of data fusion and decision fusion to determine the final decision regarding spectrum availability.

主权项

1. A method for spectrum sensing for cognitive radio, the method comprising:
detecting edges of frequency bands, detecting energies in frequency bands, and to deciding whether frequency bands area available to cognitive radio users; receiving a time-domain signal by a cognitive radio user; estimating a power spectral density of the time-domain signal; calculating wavelet transform coefficients at one or more scale factors by convolving the power spectral density with a first derivative of a wavelet smoothing function; obtaining a positive signal by taking the absolute value of all wavelet transform coefficients, and if more than one wavelet scale factor is used, combining wavelet transform coefficients for different scale; detecting one or more frequency-band edges of the power spectral density by solving for peak frequencies, wherein the peak frequencies are frequencies of the local maxima of the positive signal; defining a plurality of frequency bands as all frequencies between nearest neighbor pairs of frequency-band edges; determining a received energy value for a first frequency band of a plurality of frequency bands; comparing the received energy value to an energy threshold; and signaling frequency band availability based on the comparison between the received energy value and the energy threshold.